The present invention relates to a continuously-operating chilling cabinet for treating a mass contained in molds, for example a chocolate mass or the like.
It is known in the prior art that in order to make chocolates or chocolate bars, molds are used that comprise a plurality of wells which are filled with a fluid chocolate mass that is then set by passing it through a chilling plant.
On this subject, molding plants have become known, comprising parallel chains for conveying the molds that are filled inside a metering machine with the chocolate mass that is to be cooled.
Downstream of the metering machine, the parallel chains convey the molds in the manner of a paternoster lift through a chilling cabinet and, at the exit from the chilling plant, the molds containing the set food product are conveyed, for example, to an inverting station where the finished product is emptied out.
Known refrigerating plants use two parallel chains that engage with guides suitable for accommodating the molds as they enter the chilling cabinet. Inside the cabinet, the parallel chains first execute an ascending movement before their direction is altered near the top of the cabinet and they move along a horizontal path, at the end of which the direction of the chains is again altered to enable a subsequent descending movement and discharging of the molds, which are transferred to other conveying means.
Moving the molds (containing the product to be treated inside the chilling cabinet) by means of parallel chains moving in the manner of a paternoster lift, that is upwards, horizontally along, and downwards, has a number of disadvantages.
It is known that the dwell time of a particular product inside the chilling cabinet is decided when a plant is at the design stage, i.e. for a certain type and a particular quantity of product.
Experience teaches, however, that not all products require the same dwell time in the chilling cabinet, or in other words products require different cooling from the thermal point of view.
These needs are difficult to satisfy in paternoster lift-type cooling plants as it is very difficult to maintain the ideal thermal conditions which follow a specific curve characteristic of the cooling of the chocolate. These difficulties of achieving the right conditions arise whenever the plant cannot be run at the maximum productive speed for which it was designed. The maximum speed cannot be exploited fully with, for example, products that differ from those for which the molding plant was designed.
Hence the disadvantage that the chilling plants currently in use offer very poor flexibility from the technical point of view.
Furthermore the means such as chains, guides, shafts, walls and separators obstruct the ideal movement of air through the columns made up of the molds to be cooled, and in addition a considerable amount of thermal energy (units of cold) will be absorbed by and thus lost in the metal parts such as for example chains, guides, shafts or transmission mechanisms situated inside the chilling cabinet and continuously swept by the stream of cold air.
When using parallel chains as the means of conveying the molds through the chilling plant, it becomes understandable that the distance (pitch) between the mold supporting and lifting guides will have to be fixed. As a result, once the pitch between one mold and the next has been decided at the design stage, it will not be possible to use molds with variable dimensions, for example molds with greater thickness as required when molding larger chocolate objects.
Moreover, in paternoster lift-type chilling cabinets the molds will have to be moved along obligatory paths, i.e. they ascend a predetermined distance, before travelling along a horizontal section and then redescending down a vertical section. This requirement obviously limits the possibility of configuration of the entire molding line.
Another disadvantage typical of paternoster lift-type conveying systems is the complexity of the drive means and mechanisms.
In order to be able to produce an intermittent movement of the chains moving up and down inside the chilling cabinet, it is essential to provide cam mechanisms, boxes with special gears, drive shafts and very expensive chains. It is also necessary that the vertical movement of the molds be precisely synchronized with all the means for the horizontal conveyance of the molds; these synchronizing devices often throw up problems.
It should also be noted that food hygiene inside known chilling cabinets leaves much to be desired.
The air used for cooling the chocolate not only strikes the molds containing the product but also sweeps the conveying chains, their guides and the chain transmission mechanisms, generating an inevitable contamination of the product owing largely to residues of lubricant coming off the chains and transmission wheels, and similarly with particles of dirt that have been deposited on the chains or on their guides. There is consequently a detectable decline in product quality after the product has passed through the chilling plant.
The complexity of paternoster-type conveyors, requiring the installing of a plurality of mechanical units inside the chilling cabinet, is a hindrance to the easy periodical cleaning of the rotating units and necessitates a considerable period of time for the continuous cleaning of the supporting guides that accommodate the molds, along which guides residues of chocolate generally accumulate.
Another disadvantage which characterizes known conveyors is that during the conveyance through the chilling cabinet, the molds lose the mutual pitch--that is the distance between one mold and the next--with which they were fed in by the incoming conveyor. This fact requires the provision of very complicated and expensive synchronizing devices, partly in order that the molds can be redeposited with the desired pitch on the outgoing conveyor.
The prior state of the art has disclosed the use of a chilling cabinet comprising at least three individual magazines suitable for accommodating the molds containing the product to be cooled. Of these magazines, the middle one can be moved vertically, so allowing a gradual meandering movement the molds between the surfaces of the side magazines, thereby conveying the molds upwards and downwards. With this known solution, both the engineering demands and the space requirements are considerable, and moreover the need to give the molds a meandering movement during the setting process can give rise to the formation of waves on the surface of the product or make the molded objects conical.
Moreover, it will be necessary for the molds to enter and exit always in the same direction with respect to the chilling plant, and this limits the flexibility of the molding line. The volumes required for the chilling cabinet are great, because between the fixed side magazines it will be necessary to provide another intermediate magazine for the temporary stopping of the molds. Lastly, it is not possible to create areas of variable temperature, even though this is a requirement of a modern cooling cycle for a chocolate product of quality.